Thermostatic-controlling apparatus



July 1, 1930. w SWEATT ET AL 1,768,940

' THERMOSTATIC CONTROLLING APPARATUS Filed March 26, 1923 5 Sheets-Sheet 1 Furnace 1/0 FREDERICK 6. DEN/6 o/v 5w, I/ JW/ [NVENTORJ 5 IHHROLD MCJWf/JTT July 1, 1930. H. w. SWEATT El AL THERMOSTATIC CONTROLLING APPARATUS 6 T m R T N m O fl O E T W m N N N R 5 E m M W. w 0 n a 0 m N w R f M H R j 5 H M v 6 w a. 6. y w 4 F r a U 5 Z 7 4, M 7 4? 3 4 M re 2 2 0 4/. Z a 3 6w m M 4 2 f U 2 fi u W f/ v 7/ 6 WW M L U x 5. z 4 4 L |||||||.||M 6 2 m wt J6 R a f F M July 1, 1930. H. w. SWEATT ET AL 1,768,940

THERMOSTATIC CONTROLLING APPARATUS Filed March 26, 1925 3 Sheets-Sheet 5 ITTo/PNE Y3 Patented July 1, 1930 UNITED STATES PATENT, OFFICE,

HAROLD W. SWEATT AND FREDERICK S. DENISON, OF MINNEATOLIS; MINNESOTA, ASSIGNORS, BY MESNE ASSIGNMENTS, T MINNEAPOLIS-HONEYWELL REGULATOR COMPANY, OF MINNEAPOLIS, MINNESOTA, .A CORPORATION OF DELAWARE THERMOSTATIC-CONTROLLING APPARATUS Application filed March 26, 1923. Serial No. 627,699.

This invention relates to improvements in thermostatic controlling apparatus such, for example, as is particularly useful in conj unctionwith heating plants of the oil-burning type. It is old in such installations to employ a pilot flame of gas furnished from the usual city main connections, such flame being adapted to ignite the'vaporized fuel when a supply thereof'is turned on. It is not claimed as new in this particular application to provide'means to enlarge temporarily such a pilot flame which has been found advantageous in connection with these liquid fuel burners of the blower type. Such a pilot is flame should be kept burning during the season of use of the heating plant, hence a small economical'flame is desired. F urthermore, it is advisable to provide means to expand the pilot-flame to ignite with certainty the vaporized fuel and also to prevent the possible extinction of the small pilot flame when employed in conjunction with blowers. Means for temporarily expanding such small pilot flame for ignition of the vaporized fuel and for subsequent contraction thereof are set forth in Patent Number 1,620,796 of April 26th, 1927, to Frederick S. Denison.

This present improvement includes means for automatically breaking the blower-motor 3o circuit in the event such circuit shall have been closed, either manually'or automatically, and the ilot flame shall have been extinguished. s iich part of the improvements herein disclosedponsists generally in the provision of a thermo-bar positioned to be affected by the pilot flame and adapted when in its normally heated expanded stateby the pilot flame, to retain a switch member in its normal motor-circuit closing position and, 40 when contracted due to absence of pilot flame,

to cause the switch-member to break the-motor-circuit.

I The object therefore of this invention is to provide a new and improved thermostaticcontrolling apparatus.

Other objects of the invent-ion will more fully appear from the following description and the accompanyingdrawings, and will be pointed out in the annexed claims.

In the accompanying drawings, there has been discloseda structure designed to carry out the objects of the invention, but it is to be understood that the invention is not confined to the exact features shown as various changes ma be made within the scope of the claims whic follow.

t In the drawings:

Figure 1 is a view in vertical section of the solenoid-control for the pilot flame and showing the circuit breaker member of the blower-motor circuit in normal closing position and also showing the adjustable mounting of the apparatus in a furnace door;

Figure 2 is a View in side elevation of the apparatus, being partially broken away to show the circuit breaker member in circuitopening posltlon, the plane of section of the broken away part being substantially on line 2-2 of Figure 4; a

.Figure 3 is a view in horizontal section on the line 3- -3 of Figure 1 Figure 4 is a view in vertical section on the line 4-4 of Figure 2, showing the contact blades of the circuit-breaker member and also the means provided for operating the member-locking latch;

Figure 5 is a detailed sectional view on the line 5-5 of Figure 1, showing the pilot flame adjusting valve;

Figure 6 is a vertical sectional View on the line 66 of Figure 1 to show the gas by-pass for heating the thermo-bar; and

Figure 7 is a wiring diagram showing the controlling means adapted for substantially automatic operation in combination with a thermostatically controlled heating plant.

The selected embodiment of this invention here disclosed isshown in combination with a thermostatically controlled heating plant although it is to be understood that this novel apparatus ma also be advantageously employed in con]unction with a heating plant employing a blower-motor with a manually conrolled circuit and wherein a pilot flame is use The major portions of the apparatus shown in the accompanying drawings (with the principal exception of the circuit-controlling switch) are disclosed in the above-mentione prior co-pending application which sets forth a solenoid for enlarging a pilot flame upon energization of the blower-motor which vaporizes the liquid fuel and jets the vapor to ing. The'heat of the. pilot flame maintains a thermo-bar in a normally heated and expanded condition. Such expandedv condition maintains the circuit-breaker or switch in normally closed position so that the motor circuit, so far as this switch is concerned, is presented for opening and closing to a ther mostat or for manual operation. However, when the pilot flame is extinguished either by accident or intention, the motor-circuit is interrupted with the resultant stoppage of the .motor'and hence, the fuel supply.

- The means for furnishing a supply of combustible gas may be by way of a gas supply pipe 6 leading from a city main, or ot er usual source of supply not necessary to be shown, and adapted, through the intermediary of the novel valve structure to jet the combustible gas to a point adjacent the usual burner pan 7 of a liquid fuel burner apparatus. Of such an apparatus, there is here diagrammatically represented, a liquid fuel supply pipe 8 connected to ,a source and terminating upwardly within the end of the blower pipe 9 through which air is forced by the blower 11 driven by the belt 12 from the electrio motor 13. The vaporization of the liquid fuel by the forced air is well-known in this I art. The gas is discharged normally, during the seasonal run of the apparatus to provide a relatively small pilot flame which is adapted to be expanded by means of an electrically controlled valve device.

The valve device here shown comprises an elongated, substantially cylindrical housing 14 having opposed bosses 15 adapted to sup port and connect with the pipe 6 and the pipe 16 oppositely extending in alinement with the pipe 6. Each boss has a port 18 by means of which gas may enter within the cylindrical housing and may pass therefrom to the pilot tion of the plunger provides a valve 21 to close the inlet and outlet ports. 18 thereby to prevent passage of gas to the pipe 16 and the flame tip 20 thereby terminally carried. Ad-

d jacent this valve end of the plungeris a reduced plunger portion 22 which, when opposite the ports 18, permits passage of gas through the housing from the inlet port to the outlet port so that a relatively large amount of gas is fed to the pilot flame whereby the latter may be enlarged to ignite the vaporized fuel and also to avoid being blown out by the forced air from the blower 11 when in operation. In Figure 1, the portion of the plunger 19 which forms the valve 21 is shown in its normal passage-closing position which is also the lowered or descended position of the plunger within the housing 14. The plunger yieldably occupies such normal descended position by virtue of gravity when the housing is mounted in its upright position; however, spring-tension may be employed. As shown in Figure 1, a compression spring 23 may be mounted with its lower end terminally received within a recess 24 upwardly presented by the valve 21 while its upper end may be received within a recess 25 downwardly presented by the cap 26 received in threaded en- I gagement upon the upper end of the housing 14 and preferably closing this housing and to prevent escape of gas therefrom. The relatively small supply of gas for the normal small pilot flame is ported through a by-pass 10 provided in the housing around the valve 21 when in seated position. In this novel apparatus the gas thus by-passed may escape through the port 40 through the opposite side of the housing and opening intoanother recessed boss 15, to which the coupling 30 secures the small pilot pipe 34 having an upwardly directed tip 35 from which a small pilot flame extends. Gaseous flow through this by-pass may be adjustably regulated by means of the needle-valve 36 received in threaded engagement in the housing and terminally projecting within the by-pass 40 to constrict the same as is shown in Figure 5.

The preferred means for effecting the opening of the valve 21 is that set forth in the above-mentioned pending application and is by way of an electromagnetic coil such as the solenoid 27 of a conventional type which is positioned about the housing. An electric circuit is provided for this solenoid and, upon energization of the solenoiththe metallic plunger will be upwardly pulled in accordance with the well-known functions of such electrical apparatus.

The energization of the solenoid 27 is preferably automatically effected as, for example, by means of a thermostat, as will be subsequently. described. Furthermore, means are provided so that the energization of the solenoid is only momentary so that the plunger may be released after its upward travel and thereafter be permitted to resume its normal descended passage-closing position. In this novel device, the time-interval consumed by the plunger in moving to closing position may predetermined and adjusted to attain the desired interval which is advantageous for any given installation.

The lower end of the housing 14 is closed by means of the screw-plug 28 by which a fluid, such as oil 29, is retained therein; The lower portion of the plunger is reduced to form a stem 31 terminating in forks 32 integral with an open-ended sleeve 33. The lower edge of this sleeve forms an annular valve seat for a one-way valve so that oil may drop therepast upon ascent of the plunger and permits the sleeve freely to pass through the oil in its upward travel with the plunger.

But, subsequent deenergization of the solenoid and tensioned gravitational descent of the plunger is damped or retarded'as. the valve tensionably resumes seated position. Oil displaced by plunger-descent is slowly ported around the descending sleeve by a bypass 37, provided on one side of the housing casting. The rate of flow of the oil upwardly through the by-pass 37, and hence the length of time-interval required for damped plunger-descent, may be adjustably prede-, termined b means of the needle valve 38 adapted adustably to constrict the by-pass.

It will be noted that, as the plunger is elevated from the position shown in Figure 1, there might be a tendency to compress the air confined within the-housing between the upper end of the valve 21 and the cap 26. To

overcome anysuch tendency a conduit 43 is bored axially through the major portion of the plunger and downwardly terminates in the two angled ports 44 so that, upon travel of the plunger, the air mayoppositely pass.

Such freedom of air flow within the housing not only prevents compression above the valve 21 but also prevents any creation of a partial vacuum in the lower portion of the housing between the upper surface of the oil and the lower end of the wide portion of the plunger.

As above stated, the solenoid is energized only momentarily and, the preferred energization is effected by connecting the solenoid circuit to the apparatus set forth in the above-mentioned prior co-pending application. Such apparatus may now be described in conjunction with thediagram of Figure 7 but without going into greater detail than is necessary to explain such use of the present invention.

Broadly, Figure 7 discloses a liquid fuel burner installation of the type employing a motor 13 adapted to drive the blower 11 to deliver air under pressure to the burner. The control of the blower-motor and solenoid are so inter-related that, when the motor circuit is closed, the solenoid circuit is closed, but the latter is opened again after a predeter' mined interval while the motor circuit remains closed. Furthermore, both of these circuits may be automatically opened by thermostatic meanswhile the motor circuit is also closed thermostatically.

The thermostatic control of the motor may first be explained, thereafter the control of the gas-valve solenoid circuit, and finally the improved thermostatic emergency cut-out.

Generall considered, there is provided a switch having a pair of spaced terminals and a circuit-closer cooperable therewith to complete a circuit through such terminals. This circuit-closer ispreferably operable by means of an electric current operating through an armature and solenoids of opposite polarity. Means are provided singly to energize these two solenoids or coils so that the armature may be moved in a direction to effect the desired opening or-closing of the switch. The means here shown for singly energizing the coils is a thermostatic device.

The lead 45 of the motor 13 is directly con nected to the side 51 of the main line circuit.

while the connected leads 46 and of the motor are connected to the other side 52 of the main line through the novel cut-out 39 and a circuit-closer 53 and its spaced blades 50.

This circuit-closer is shown in Figure 7 in closed position but is adapted to be upwardly rocked to open the motor circuit.

A convenient mode of rockin this circuit-closer bothout of andinto clrcuit-closing position is provided b means of the rockshaft 54 which carries tie circuit-closer 53.

This rock-shaft is adapted to be rocked by an armature 55 reciprocably mounted within the alined cores of two solenoids which are adapted singly to be energized to produce opposite polarity so that the armature may be selectively moved in opposite directions. One solenoid may be referred to, as the upper or circuit-closing coil 56 and the other, as the lower or circuit-opening coil 57.

The selective energization of these two coils is effected, in this apparatus, by means of a thermostat. Each coil is provided with a circuit leading to a suitable source of electric energy and each such coil-circuit is adapted to be electromagnetically closed or opened by the thermostat and the parts are so arranged that the upper or circuit-closing coil is energized by the cold side of a thermostat circuit while the lower or circuitopening coil is energized by the hot side of the thermostatic circuit.

Each coil is provided with a circuit connected to the main line. The lower coil 57 has a wire 58 leading from the top of its winding to a contact blade 59 insulated from a complementary contact blade 61 having a wire 62' connected to .the lead 60 of the motor circuit. The lower coil also has a wire 63 leading from the bottom of its winding to lower coil 57 is provided with its circuit which may not only be opened and closed by means of an armature at one point but also may be opened and closed at another point across the blades 59 and 61. The closure of this latter break is by means of a circuitcloser 68 carried by the rock-shaft 54 and operable thereby. This circuit-closer 68 is thus co-operable with the motor'circuit closer 53.

The upper coil 56 has a wire 69 leading from the bottom of its winding to a contact 71 projecting for'circuit-closing engagement below a movable aimaturecontact 72 operably to make-and-break this upper coil circuit. This armature-contact 72 is normallv and yieldably held out of engagement with the contact 71 by any suitable means.

The armaturecontact 72 is electrically connected by the w1re 73 to the lead of the motor circuit. As electromagnet 74 is positioned below the armature-contact 72 in order, upon energization, to draw the contact 72 to the contact 71 to close the coil circuit across this break. ;The electromagnet 74 is adapted -to be energized by the cold side of the thermostat in order indirectly to start the motor and, it may be noted in passing, that the gas-valve-solenoid circuit is adapted to be closed when the circuit through this upper coil 56 is closed. The wire 75 leads from the upper portion of the coil 56 to theknife blade 76, electrically insulated from the complementary knife blade 77 connected by the. wire 78 to the main line 52. The break across the blades 76 and 7 7 is adapted to be closed by a circuit-closer 79, carried, similarly to 4 the circuit-closer 68 by the rock-shaft 54. This circuit-closer 79 is here shown in dotted lines in order to indicate that it is not in circuit closing position because the circuit-closer 68 is so shown, it being understood that these circuit-closers are 0 positely moved. That is, when the circuit-c oser 68 is in closing position, the circuit-closer 79 is in circuit-opening position and vice versa.

The electromagnets 67 and 74 are adapted to be selectively'energized, preferably by side of the transformer 81.

a thermostatic circuit. Such circuit may derive its electricenergy from the motor circuit throughthetransformer 81. Thethermostatic circuit comprises the .usual hot and cold sides with thermo-bar connection. Such a thermostat is diagrammatically represented in Figure 7, wherein the usual thermo-bar 82 iselectricallyconnect'edto theseconda winding of the transformer by means of t e wire 83. The hot contact 84 has a wire 85 terminating in theknife blade 86 whichis insulated from its complementary knife blade 87 having a wire 88. running to the upper portion of the winding of the electromagnet 67 while the wire 89 runs from the lower ortion thereof to the secondary or low-tension side of the transformer 81.

The cold side contact 91 is connected by the wire 92 to the knife blade 93 similarly insulated from its complementary knife blade 94 which in turn isconnected by the wire 95 to the upper portion of the winding of the electromagnet 74 having its lower portion electrically connected by the wire 96 to the wire 89 of thesecondary or low-tension Circuit-closers 97 and 98 are carried upon the rock-shaft 54 and are similar in construction and operation to the circuit-closers 68 and 79 carried at the opposite end of the rock-shaft.

Before describing the incorporation of the gas-valve solenoid circuit and the emergency cut-out in this apparatus, the operation ofthe above parts may-be first explained.

In the position of the parts in Fi ure 7, the apparatus'is shown in position w erein the 'thermo-bar 82 has previously been bent by .room temperature to cause electrical contact with the hot side contact 84 whereby current may flow from the secondary winding of the transformer 81,,th1'ough the presented circuit, as follows: Wire 83, thermo-bar 82, hot contact 84, wire 85, blade 86, circuit-closer 97, blade 87, wire '88, electromagnet 67, wire 89, and back to the secondary winding. The electromagnet 67 is thus energized with the result that the armature-contact 65 is downwardly pulled to effect electrical connection with the contact 64, whereby the following circuit is closed; lead 45, wire 66, armature-contact 65, contact 64, wire 63, opening-coil 57, wire 58,

blade 59, circuit-closer 68, blade 61, and wire transformer 81, through the thermo-bar contact'9gl, wire 92, blade 93,.circuit-closer 98,

' blade 94, wire 95, electromagnet 74, .wire 96,

. mentary. Such momentar to the secondary winding. The electromag net 74 is .thereby ener ized to attract the armature contact 72 to c ose with the contact 71 whereby a circuit is presented from the main line side 51, motor lead 45, wire 73, armaturecontact 72, contact 71, wire 69, closing coil 56,

wire 75, blade 76, circuit-closer 79, blade 77, wire 78, to the other main line side 52. The closing coil 56i's this energized, the rockshaft returned to the full-line position in Figure 7 and the motor circuit. is closed, and the motor, blower and burner function.

Turning now to the incorporation of the gas-valve, solenoid circuit in this apparatus, it may be noted that, when the rock shaft 54 is returned to its Figure 7 position, the circuit-closers 97 and 68 are likewise returned to the indicated closed position, while the circuit-closer 79 is simultaneously moved by the rock-shaft to open position so that the circuit through the closlng coil 56 is opened. Thus, by connecting the solenoid 27 with the circuit of this coil 56, the solenoid 27 may be energized when the coil 56 is energized to start the motor. To this end, a wire 99 is con-. nected to the coil wire 69 and to the winding of the solenoid 27. The other end of this winding is connected by the wire 101 to the motor lead 46. Thus, coincident with energization of the motor-starting coil 56, the solenoid 27 will be energized. Furthermore, as such energization of the coil 56 is only momentary (because its circuit isimmediately openedby-the circuit-closer 79) so also, the

energization of the solenoid is only moenergization of the solenoid is suflicient to e evate the plunger 19, so that, upon immediate de-energization, its timed descentmay cormnence. When the plunger is elevated, the valve 21 israised above the alined ports 18 so that the-full or. enlarged flow of gas is had through the pipe .16 togtherfiame tip 20 from which the flame plays upon the burner pan 7.

Reference may now be had to the emergency cut-out or circuit-breaker which is thermostatically operated for the automatic opening of the motor circuit when the small auxiliary pilot flame has been extinguished from any cause.

The housing for this circuit-breaker, its

thermo-bar, the two gas pipes and associated parts is preferably made with a ball-like portion 102 which is adapted adjustably to project within a substantially circular opening 103 provided'in the usual furnace door 104 .and is mounted substantially to provide a universal joint. The socket. is provided by the two plates 105 and 106 having a'rcuately curved inner surfaces to receive the portion 102. Preferably the arc of curvature of the two plate surfaces is struck upon a slightly. shorter radius than the curvature of the ball like portion 102 in order that upon tightening of the screws 107, the portion 102 may be held in a relatively fixed adjusted position so that the gas flame may be accurately projected to the burner pan 7. F orwardly of the portion 102 is a cylindrical section 108 which terminates; with the barrel 109. The forward end of the pipe 34 is closed and terminates in the section 108 and the small pilot flame tip 35 extends upwardly to'project the gas through the opening 111 in the horizontal wall 110 provided within the cylindrical section 108. Thus the small flame burns Within the path of gas projected from the tip 20.

Furthermore, a slot 112 is cutin the pipe 34 rearwardly. adjacent the tip 35 sothat a relatively small amount of gas may escape there, through and 'burnadjacent a therm0-bar113 secured to the pipe 34 by the screws and spacing blocks .114. The housing rearwardly terminates in'another cylindrical section 115 with an upwardly projecting wall 116. This rear end of the housing is closed by a suitably shaped cover 117. In order to supply air to the-small pilot pipe 34, its underface and the under face of the cylindrical sectiony115 are provided; with 'diagonally'alined apertures 118. The front end of the pipe 16 and its tip 20 are conveniently supportedby an integral boss 119 inwardly depending from the balllike portion 102.

The circuit-breaker or switch has its member mounted within the substantially rectangular space formed by the'upright wall 116 and the cover 117. The relatively fixed members consist of the two spaced blades 121 and 122 mounted upon the insulated base 123 secured to the cover. The wire 46 from the 'motor is electrically connected to the blade 121 while the wire 60, which forms a continuation of this motor lead to "the main l ne side 52, is electrically connected to the blade 122.

These blades are thus in series with one lead from the motor to the main line and hence, unless the gap between the blades be suitably closed, the motor circuit is interrupted. The circuit-closer is provided by the U-shaped knife 124 carried by the lever 125 which is pivoted upon the pin 126 and, projecting through the cover 117, terminates in the insulated handle 127. The compression sprin 128 mounted between the cover rib 129 an the lever tends to move the lever from its circuit-closing position shown in Figure 1 to the opening position shown in Fi ure 2.

A thermostatically controfi provided to retain the lever knife in circuitclosing position to which the knife is adapted ed detent is to be manually moved uponlighting of the small pilot flame. This detent is adapted automatically to release the knife, upon extinction of the small flame, whereby the knife moves to circuit-opening osition. Such detent is rovided by the atch 131 pivotally carried etwen brackets inwardly projecting from the upright wall of the cover 117. The normal position of the latch may be referred to as that indicated in Figure 1 wherein the latch is shown in elevated position so that its notch is engaged by the downwardly terminal toe of the knife lever 125. Means are provided to retain the latch in its normal position when the thermo-bar 113 is in its expanded convex form shown in Figure 1 due to heat from the ignited gas escaping through the slot 112. The small pilot flame is composed substantially of the ignited gas from the slot 112 and that from the jetting tip 35 which directs a portion thereof more accurately into the path of gas delivered by the main tip 20. The above-mentioned latch-retaining means includes a lever 132 pivotally mounted in a bracket carried by the thermo-bar ad'acent its middle portion as is indicated in igure 1. The portion of the lever on the front side of its pivotal mounting is relatively short and upwardly terminates in a finger 133 adapted to abut against the under face of the boss 119 so that any upward movement of themiddle portion of the thermo-bar is multiplied and communicated to the rear portion of this lever which carries a. pair of yoke members 134 pinned thereto. As is shown in Figure 4, these yoke members are shaped. to pass upwardly upon each side of the pipe 16 and pass through apertures in the wings 135 which integrally and laterally extend from the latch 131. The latch is tensionably upwardly held by means of a compression spring 136 coiled about each yoke member and held between collars 137 and the under face of the wings.

The latch thus yieldably held in elevated position upon expansion of the thermo bar and in the path of thepointe'd lower end of the lever 125'rso that, when the handle is moved from the position shown in Figure 2 to that of Figure 1, the lever end may ride over the latch end portion and enter the notch so that the lever will be locked in such cir- Having thus described our invention whatwe claim as new and desire to secure by L tters-Patent, is: x

1. In a device of the class described a pilot pipe having a flame orifice, a switch having is applied the thermo-bar bulges in one direction to dispose the latch at latching position and the arrangement further being such that on extinction of flame the thermo-bar moves 'in an opposite direction to move the latch from latching position.

2. A device of the class described having a gas supply pipe, a pilot pipe arranged to ignite gas delivered by the first mentioned pipe and having a flame orifice, a switch, a thermo-bar element arranged to be heatedby the pilot flame, and connected at 0 posite ends to form abridge adapted to be bowed when heated, a lever pivoted upon the thermostatic element having one arm engageable with the first mentioned pipe, and connections between the opposite arm of the lever and the switch arranged to open and close the switch, as the thermostatic element moves in opposite directions.

3. A casing having a burner pipe leading therefrom withthe casing open to allow delivery of-fuel outwardly from the pipe, a

pilot plpe adjacent the burner pi e and having a tip arranged to deliver ame at the flame end of the burner ipe, and further having a slot as an auxiliary flame orifice, a thermo-bar connected at two points only to the burner pipe to bridge the auxiliary orifice, a switch having a movable element, a

latch for normally holding the switch closed,

a lever upon the thermo-bar having one arm I engaging the burner pipe as a top, and connections between the opposite arm and the latch such that when the thermo-bar is heated the latch remains in latching position, and when cooled withdraws the latch from latching position.

4. A ilot pipe having a flame orifice, a thermoar connected at two points to the pipe, in a manner to have flame from the orifice play upon the thermo-bar at a point intermediate its connecting points, saidilot pi e having a burner ti passin loosey th-ro i gh the thermo-bar. p g 5. A pilot pipe having two flame orifices, a thermo-bar connected to the pipe at two points spaced apart and arranged to bridge one of the orifices, and to allow flame from the other orifice to burn at a point outwardly beyond 'the thermo-bar. I

6. A pilot pipe having a burner tip, and a flame orifice arranged adjacent the tip, a thermo-bar connected to the pipe at two points spaced apart in a manner to bridge the flame orifice, the arrangement being such that flame produced through the orifice causes I the element to buckle away from the ipe, andsaid tip being arranged todeliver ame 5 at a point outwardly beyond said bar.

In witness whereof, we have hereunto set "our hands this 15th day of November, 1922. I

' HAROLD W. SWEATT.

FREDERICK S. DENISON. 

